#include <iostream>

using namespace std;
typedef long long LL;

const int N = 5010;
int n,m;
int a[N][N];
int f[N][N]; //前缀和矩阵



int main()
{
    cin >> n >> m;
    while(n--)
    {
        int x,y,v;
        cin >> x >> y >> v;
        x++,y++;
        a[x][y] += v;
    }
    n = 5001;
    for(int i = 1;i <= n;i++)
    {
        for(int j = 1;j <= n;j++)
        {
            f[i][j] = f[i-1][j] + f[i][j - 1]-f[i-1][j-1]+a[i][j];
        }
    }
    int ret = 0;
    m = min(m,n);//如果炸弹很大,就拿全部的
    for(int x2 = m;x2 <= n;x2++)
    {
        for(int y2 = m;y2 <= n;y2++)
        {
            int x1 = x2 - m + 1,y1 = y2 - m + 1;
            ret = max(ret,f[x2][y2] - f[x1 - 1][y2] - f[x2][y1 - 1] + f[x1 - 1][y1 - 1]);
        }
    }
    cout << ret << endl;

    return 0;
}